80 LANDS OF THE ARID REGION OF THE UNITED STATES. 
Two of the stations, Salt Lake City and Camp Douglas, lie within the 
zone of climate modified by Great Salt Lake, and a brief inspection of the 
table will show how greatly their climate is influenced. As a general rule, 
the localities of greatest precipitation in the Rocky Mountain Region have 
so great altitude that their summer temperature does not permit agriculture, 
but Salt Lake City, with an altitude 1,000 feet below the average of the 24 
stations, and a temperature 4° above the average, has a rainfall 11 inches 
greater than the average; and Camp Douglas, 3° warmer than the average 
and 250 feet lower, has a rainfall 5 inches greater. If the two stations are 
compared with those which lie nearest them, the contrast is still more 
striking. Camp Halleck, 130 miles west of the lake, and 600 feet higher 
than Camp Douglas, has a rainfall of 11 inches only. Fort Bridger, 90 
miles east of the lake and 1,600 feet higher than Camp Douglas, has a rain- 
fall of 8 inches. Camp Floyd, 380 miles south of the lake and sheltered 
from its influence by mountains, receives only 74 inches. But Salt Lake 
City and Camp Douglas, lying between the lake and the Wasatch Range, 
record respectively 24.8 and 18.8 inches. 
In fine, it appears that the climate of the eastern shore of Great Salt 
Lake is decidedly exceptional and approximates in humidity to that of 
Central Kansas. The fact that it admits of dry farming gives no warrant 
for the belief that large areas in the Arid Region can be cultivated without 
irrigation, but serves rather to confirm the conclusion that the limit to 
remunerative dry farming is practically drawn by the isohyetal line of 22 
inches. Even in this most favored district the yield is so small that it can 
be doubled by irrigation, and eventually water ditches will be carried to 
nearly all the land that has yet been plowed. 
